Field of the Invention
The present invention relates to an imaging apparatus and a control method therefor.
Description of the Related Art
There is panning as one of camera photographing methods. The panning is, for example, a scheme of photographing while causing a camera to follow a motion of an object which is moving in the horizontal direction. At the time of panning, a shutter speed is generally set to a greater number of seconds and decreased to produce a dynamic feeling in the object. As the shutter speed is decreased, a flow level of a background increases and a more dynamic feeling in the object is produced. However, a camera shake or the object shake easily arises.
There are two functions which can be conceived as a function of assisting panning. The first function is a function of detecting an image shake in an object and a camera and optically correcting the object shake in accordance with the image shake using a shift lens. The second function is a function of automatically setting a shutter speed so that an image shake amount of a background becomes constant.
Japanese Patent Laid-Open No. 2006-317848 discloses an imaging apparatus that detects a difference between an object speed and a camera shaking speed and correcting an image shake amount corresponding to the difference using a camera shake correction function. In addition, Japanese Unexamined Patent Publication No. 2008-136174 discloses an imaging apparatus of detecting a motion of a moving body inside a screen as a motion vector and calculating an exposure time at which a desired flow blurring width is acquired in accordance with the motion vector.
In Japanese Patent Laid-Open No. 2008-136174, panning photographing is performed by moving a correction lens in association with a motion of a moving body in a fixed state of the imaging apparatus and a difference between motion amounts of a main object (moving body) and a background (still body) is obtained as a motion vector in order to calculate an exposure time. However, for example, when the main object has low contrast, the motion vector may not be obtained with precision and it may be difficult to calculate an exposure time at which a desired flow blurring width is acquired.